Apparatus for introducing a latent crimp into a yarn

ABSTRACT

A yarn transport roll is divided into annular regions and magnetic lines of force are introduced into one narrow annular region for heating purposes.

United States Patent [72] Inventor l'lendrinus Selnpel Arnhem, Netherlands [21] Appl. No. 838,998 [22] Filed July 3, I969 [45] Patented Sept. 14, 1971 [73] Assignee American Enka Corporation Enka, N.C. [32] Priority July 8, 1968 [33] Netherlands [31 6,809,645

[54] APPARATUS FOR INTRODUCING A LATENT CRIMP INTO A YARN 1 Claim, 3 Drawing Figs.

[52] 0.8.01 2l9/10.61, 219/469 [51] Int. Cl 1105b 5/00,

HOSb 3/02 Primary ExaminerJ. V. Truhe Assistant Examiner-L. H. Bender Attorney-Francis W. Young ABSTRACT: A yarn transport roll is divided into annular regions and magnetic lines of force are introduced into one narrow annular region for heating purposes.

mm sin 4 m mv mrmn HE NDRINUS SEMPEL ATTO In a known method for crimping yarn, one of the convolu- 10 tions of the yarn around a draw roll and a separator roll is heated by an electrically heated roll which is driven by the draw roll. The electrically heated roll is provided with a circumferential groove through which the yarn is passed in order to be heated on one side.

Advantageously, this invention provides a method and apparatus for heating the yarn on one side without the use of a separate heater roll.

Thus this invention contemplates a method for introducing a latent crimp into a yarn which comprises passing an attenuated yarn through a zone along a helical path over at least one roll, and heating the yarn on one side the zone to a temperature at which a latent crimp isforrned therein, the latent crimp being introduced into or formed with the yarn on a narrow zone or portion of the roll over which the yarn travels along a helical path.

In accordance with the method of this invention, when the yarn is drawn between at least one feed roll and one draw roll over which it travels along a helical path, a latent crimp may be introduced into the yarn on the draw roll.

This invention also is concerned with a roll for transporting yarn, especially'a draw roll, characterized in that the outer sleeve of the roll has a narrow zone which is heatable to the temperature at which latent crimp is formed in a thermoplastic yarn.

Although with this embodiment of a draw roll the yarn may be wrapped around the draw roll in a plurality of convolutions, the yarn is heated only over a limited portion of the total length along which it is in contact with the draw roll.

A very suitable transport roll is further characterized in that the roll comprises a rotatable roll sleeve, and an inducing element or means for producipg magnetic lines of force fixedly mounted in the interior of the sleeve, said means having a magnetizable core and an exciting coil provided on the core; and the sleeve having a narrow annular zone that serves as an induced element or means for closing the magnetic lines of force produced by the inducing element whereby the zone is heated.

With an appropriate choice of the shape and the dimensions of the core and the exciting coil, this embodiment of the roll will insure selective heating of the roll sleeve, i.e., heat is applied at least substantially to a predetermined narrow portion of the circumferential surface of the roll sleeve.

A preferred embodiment of the roll is also characterized in that the roll sleeve is on its inside surface provided with at least two circumferential grooves which define the narrow heatable zone and which comprise means for preventing the flow of heat to other portions of the roll sleeve.

This invention is also directed to an apparatus for introducing latent crimp into a yarn which comprises means for feeding a yarn to a draw roll, said draw roll having a sleeve with means for heating a narrow zone on the sleeve to a temperature for forming a latent crimp in the yarn as it travels in a helical path over the sleeve. Advantageously this apparatus may also be provided with a friction body or means, e.g., a pin, which bears against the yarn before the yarn comes into contact with the draw roll. it has been found that the use of the friction body leads to a decrease of the number of yarn filament breaks and also to an improved crimp evenness.

The apparatus and method of the invention will be further understood from the following detailed description and by reference to the accompanying drawings, in which:

FIG. 1 shows an apparatus of the invention for the spindrawing of nylon-6 carpet yarn;

FIG. 2 shows a draw roll of the invention used with the apparatus shown in F IG. 1; and

FIG. 2a shows another embodiment of the apparatus of the invention.

A yarn or bundle of filaments l, supplied by a spinning apparatus (not shown), is passed to a feed roll 2 and a separator roll 3.

The filament yarn or bundle is made up of 64 filaments of poly-epsiloncaprolactam (nylon-6) and after drawing its total denier is 1,140. The feed roll 2 is driven at a circumferential speed of 400 meters per minute. The yarn makes five wraps around the feed roll 2 and the idler roll 3 and is then passed to the pair of driven draw rolls 4 and 5. The yarn is given five wraps around the two draw rolls 4 and 5 and then the yarn is, at a speed of 1,700 meters per minute, passed via a guide roll 6 and a traverse drum to a support 8. On the support the yarn is wound into a package 9.

In its third convolution around the draw roll 5 the yarn passes over a narrow zone which is heated to a maximum temperature of approximately 220 C.

FIG. 2 is a schematic representation of the construction of the draw roll 5. This roll comprises a chromium-plated steel sleeve 10 which is via hub 11 fastened to a driving shaft 12 for 5 rotation in the direction indicated by the arrow.

ment supports a core 16 which consists of a number of lamination packs that are arranged about the axis of rotation of the roll and that are built up of U-shaped laminations which have been punched from dynamo plate.

Provided around the core is an exciting winding 17 which is connected to a source of alternating current (not shown). One

of the magnetic lines of force is indicated by the closed loop 18. In the zone between the grooves 13 and 14 the roll sleeve 10 is heated as a result of hysteresis and eddy current losses. The grooves will prevent heat from flowing to other portions of the roll sleeve, so that in its third convolution (indicated in FIG. 2 by the reference numeral 19) the yarn will come into contact with a portion of the sleeve surface that is heated to a temperature of approximately 220 C. The speed of the yarn and the length over which it comes into contact with the heated zone during its third convolution are such that it is heated on only one side. Immediately thereafter the yarn is cooled in its convolution round the nonheated roll 4.

The crimp contraction of the yarn produced by the method of this invention was found to be very regular, its value being approximately 25 percent. It is defined as (L,L )/L X100 percent, where L, represents the length of the yarn in a skein before the crimp is developed and L refers to the length of the yarn after the crimp has been developed in water of C.

The method of this invention will be further understood by reference to the following example.

EXAMPLE A yarn treated on the apparatus illustrated in FIGS. 1 and 2 0 with the heating of roll 5 switched off was compared with the yarn produced by the method of this invention. The carpet nylon yarn with a latent crimp of this invention was found to have a lower contraction tendency after it had been wound into a package, a higher breaking strength and a lower hotwater shrinkage (the temperature of the water being 98 C.). Specifically, the breaking strength and hot-water shrinkage of the yarn drawn at a ratio of 4:2, with the roll 5 in a nonheated condition were found to be 5.6 g.p.d. and 21 percent, respectively; whereas for the yarn with a latent crimp produced by this invention these values were 6.24 g.p.d. and 12.6 percent, respectively.

Advantageously, a friction body in the form of a pin, a plate, or the like, which bears against the yarn just before the yarn comes into contact with the heated zone of draw roll 5 has been found to have a favorable effect on the evenness of the crimp. The location of a pin for this purpose is schematically indicated by reference numeral on FIG. 2a.

Although with the embodiment of the apparatus shown in H0. 1, the invention is used on a spindrawing machine it will be understood that its use is not limited to this application. The apparatus can also be used on apparatus in which drawing does not immediately follow spinning. Moreover, it is not necessary that use he made of two draw rolls for the drawing operation. In certain cases, it may suffice to use one draw roll and a separator roll and to pass the yarn, in one of its convolutions round the draw roll and the separator roll, over the heated zone of the draw roll. If desired, the yarn after it has been in contact with the heated zone, may be cooled by subjecting it to the action of a jet of gas such as air. Alternatively, it is possible to cool the draw roll over a zone with which the yarn comes into contact after it has passed the heated zone.

Also, it will be appreciated that immediately after the yarn has been heated on one side, the yarn may be subjected to a heat treatment for the purpose of fully developing the latent crimp therein. Very favorable results have been obtained by the application of the method described in the US. Pat. application Ser. No. 783,089. By this method, yarn with a latent crimp, while in a warm state, is subjected to a direct second crimping treatment by means of stuffer box crimping, gear crimping, air texturing, or other direct crimping process.

It will also be appreciated that the term "attenuated yarn" is used to refer a yarn which has been drawn or is being drawn or otherwise treated to effect the molecular orientation thereof.

What is claimed is:

l. A roll comprising:

a. a rotatable shaft;

b. a cylindrical sleeve fastened to said shaft;

0. means for closing magnetic lines of force within a narrow annular region of the cylindrical sleeve;

d. a magnetizable core fixedly mounted adjacent the inner surface of the narrow annular region, corresponding in width to said narrow annular region;

e. an exciting coil provided on said core; and

f. means for connecting said coil to an alternating current.

g. said means for closing the magnetic lines of force comprises two circumferential grooves on the inner surface of the cylindrical sleeve for defining the narrow annular 

1. A roll comprising: a. a rotatable shaft; b. a cylindrical sleeve fastened to said shaft; c. means for closing magnetic lines of force within a narrow annular region of the cylindrical sleeve; d. a magnetizable core fixedly mounted adjacent the inner surface of the narrow annular region, corresponding in width to said narrow annular region; e. an exciting coil provided on said core; and f. means for connecting said coil to an alternating current. g. said means for closing the magnetic lines of force comprises two circumferential grooves on the inner surface of the cylindrical sleeve for defining the narrow annular zone. 